Insulin Human (30/70 Biphasic)

Biphasic human insulin 30/70, often abbreviated BHI 30, is a premixed insulin preparation, meaning it contains a fixed blend of two kinds of insulin in one vial or pen ^[1]. As named in Europe, the 30/70 ratio refers to 30 percent soluble, short-acting regular human insulin combined with 70 percent intermediate-acting isophane (NPH) insulin; the same product is labeled 70/30 in the United States ^[1]. Both insulin fractions are ordinary human insulin made by recombinant DNA technology, with the slower fraction rendered longer-acting by complexing it with protamine ^[1].

Premixed insulins were developed to spare people the inconvenience and error of drawing up and mixing two separate insulins themselves, combining basal and mealtime coverage in a single injection ^[2]. Roughly two of every five insulin-treated people with diabetes worldwide have been estimated to use premixed formulations, largely for this practicality ^[3]. Biphasic human insulin was the conventional premix before rapid-acting analog premixes, such as biphasic insulin aspart, were introduced to improve after-meal control ^[1].

The 30/70 premix is used chiefly in type 2 diabetes, typically injected twice daily before breakfast and the evening meal, to provide both prandial and basal insulin with fewer injections than a full basal-bolus regimen ^[1]. Clinical reviews find that premixed insulins give better overall control than intermediate or long-acting insulin used alone, though the newer analog premixes achieve somewhat better after-meal glucose levels and allow more flexible dosing relative to meals ^[1]. Studies comparing biphasic human insulin with analog premixes and with basal insulin report broadly similar rates of serious low blood sugar, with differences mainly in postprandial glucose and injection timing ^[3][4].

Biphasic human insulin 30/70 is supplied as a cloudy suspension in vials and prefilled pens under brand names such as Humulin 30/70, Novolin 30/70, and Mixtard 30 ^[2]. Its risks are those of insulin generally, above all hypoglycemia, which can occur when the fixed dose does not match food intake; because the timing of the two components is set, careful coordination with meals is important ^[1]. Other possible effects include weight gain, low blood potassium, injection-site reactions, and changes in the fat under the skin at overused injection sites ^[2].

This is a prescription injectable. Low blood sugar is the main risk, and with a premix the timing matters: because the ratio is fixed, meals need to be regular and reasonably consistent or lows and highs can follow. Human premix insulin should be given about 30 minutes before eating, unlike faster analog premixes. It can cause weight gain, and it lowers blood potassium. Injection sites should be rotated to avoid lumps and fat changes. The vial or pen must be gently rolled to resuspend the cloudy insulin before each dose, since an uneven mix changes the delivered ratio. It is not suitable for intravenous use or for rapid correction of very high sugars.